Facsimile telegraphy



y 1930- J. BAIRD 1,757,352

FACS IMILE TELEGRAPHY Q le June 7'. 1928 2 Sheets-Sheet 1 y 1930- I J. BAIRD 1,757,352

I FACS IMILE TELEGRAPH! Filed June 7, 1928 2 She etS-Sheet 2 Patented May 6, 1930 UNITED STATES PATENT OFFICE JOHN LOGIE IBAIRD, OF LONDON, ENGLAND, ASSIGNOR T0 TELEVISION LIMITED, OF

LONDON, ENGLAND, A BRITISH. COMPANY FACSIMILE TELEGRAPHY Application filed .Tune 7, 1928, Serial No. 283,695, and in Great Britain June 20, 1827.

Thiainvention is for improvements in or relating to facsimile telegraphy, that isto say, the reproduction by telegraphic means of a drawing, photograph, document or the like. The word drawing will be used in this specification to indicate the ob'ect whereof a facsimile is t be reproduce at the receiving station.

This invention comprises in facsimile telegraphy, a method of transmission wherein the drawing is cut into a series of strips, the

strips are arranged (for example joined) end-to-end to form a continuousband, and

the band is used in transmitting apparatus wherein the exploration is effected as ,toone direction by the longitudinal movement of the band itself and as to the other direction by 23 traversal laterally of the length of the ban This invention also comprises a, method of reception in facsimile telegraphy wherein the picture is received as a continuous band, consisting incutting the received band in appropriate sections and assembling the sections side-by-side to reconstitute the complete picture.

The construction of the continuous band may be efl'ected in various ways, either by securing the various strips of the drawing directly together, or by mounting them upon a perforated strip such as a kinematograph film. The strips may be joined end-to-end or a small gap may be left between successive The exploring mechanism of the trans mitter may be of any desired type which gives exploration in a direction transverse to 1 the length of the band passing through the apparatus, themovement of the band itself providing the exploring movement at rightangles to the first-mentioned movement.

At the receiving station a photographic film or other light-sensitive medium in the form of a long bandis used to receive the signals. It is moved longitudinally in synchronism with the movement of the band at the transmitting station, and a lateral exploring device of any desired type is also operated synchronously with the lateral exploration at the transmitting station. A

light controlled by the incoming signals is projected upon the photographlc film, the intensity of the light being controlled in the usual manner so as to produce light and shade eflects corresponding to those of the drawing being transmitted.

In the accompanying drawings Figure 1 is a perspective view of a transmitting apparatus which may be employed incarrying out a method of transmission according to the present invention;

Figure 2 is a side elevation of the apparatus, shown in Figure 1; and

. Figure '3 is a plan of the apparatus shown in Figure 1.

In the apparatus shown in the drawings, a series of lenses 2 (Figure 1) is mounted in a circle on a disc 4 which revolves infront of the moving band 6 which, as hereinbefore mentioned, is formed from a series of strips, arranged end-to-end, cut from the drawing which is to be transmitted.- The lenses 2 1n their operative position are moved by rotation of the disc 4 transversely of the length of the band 6 and in so moving, traverse an image of that portion of the band which at any instant is illuminated, as presently will be described, across a light-sensitive cell 8, for instance a selenium cell. The band is moved lengthwise, by meansto be described,

its movement being slow compared with the lateral traversing movement, so that; in effect, the band 1s divided 1nto transverse lines which are successively traversed over.

the cell 8.

The means for moving the band lengthwise to unwind the bandfrom the reel 12. The

reel 10 has fast-upon its shaft a worm-wheel 14 driven by a worm 16 on a shaft 18 which is connected by a clutch 20 to the shaft 22 of an electric motor 24 (Figures 2 and 3). The 1 disc 4 is fast upon the shaft 22 and is thus also driven by the motor 24. Between the two reels'10 and 12, there is a guide 26 for the band in which guide an opening 28 (Figure 3) is formed so as to allow light from two lamps 30 to fall upon the band. Each lamp is provided with a concave mirror 32 for concentrating the light from the lamp upon the band, the direction of each beam of light being at an angle of about 45 to the length of the band, as shown in Figure 3, so as to secure an even illumination of the portion of the band exposed by the opening 28. .It will be seen from an inspection of Figure 3 that the parts are so arranged that a rightline passing through the cell 8 and the opening 28 is cut by the centres of the lenses 2 as they sweep past the opening 28 in the rotation of the disc 4. T he clutch 20 connecting 'in front of a fixed slot. which lies transverse- 1y oft-he film, this arrangement projecting successive points of the band on to the cell.

Also, a disc with a series of holes around its circumference, or a revolving polyhedron mirror, may be used.

Instead of causing the image to traverse the cell, the lateral traversal may be obtained by moving a spot of light across the band,

somewhat in the manner described in British patent specification No. 269,658 (applicant-s J. L. Baird and Television Limited). It will be appreciated, however, that the spot of light has merely to traverse the band in one direction instead of having-two component as by revolving lenses; shutters, mirrors,

pra'isms' or the like, and the arrangement may such as to operate by means of light re- I flected from the surface of the band if the "be of the samegeneral character as that of "flexible sheets which comprises cutting the picture be opaque, or by light transmitted through it if it be transparent.

The apparatus at the receiving station may the transmitting apparatus illustrated here: in. That is to say, it will com rise means for moving length-wise. a ban of photoraphic' film or the like, suitably shielded rom light except for an opening in the shield, like the. opening 28 shown in Figure 3. Light from a suitable source situated in front of theopening/in the shield and controlled by the incoming signals from the transmitting apparatus will fall upon the portion of the film exposed at the said opening, exploration being effected by a .disc with lenses similar to the disc 4 and lenses 2 and similarly arranged in relation to the opening and tothe light-source asare the disc 4 and lenses to form a completed picture.

rectly on a glow-discharge lamp, or by means of a 1nagnetieally-controlled shutter or equivalent device with any other suitable source of light. The traversal of the light over the photographic film may be effected in any desired manner, by means of revolving lenses as just mentioned, or by shutters, mirrors or prisms, it being necessary only that synchronism should be maintained between the. transmitting and receiving stations; this may be elt'ected by means of av special synchronizing signal transmitted at regular intervals, say at the end of each strip into which the original drawing is divided.

It will be appreciated that by using the present invention, a drawing of any size can be transmitted by a single apparatus, since it can be divided into strips of a standard width to suit the apparatus, and any length of these strips can be transmitted; the band at the receiving station is cut into appropriate lengths corresponding to the original' strips (these being indicated for example by the synchronizing signal) and the Various portions assembled together side-by-side to reconstitute the original drawing and provide a facsimile thereof.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. A 'method of transmitting pictures which comprises separating the picture into a plurality of parts, arranging the parts in contiguous relation to form a strip, moving the strip in the direction of its length and simultaneously scanning the strip in a direction transverse thereof, and converting the resulting light waves into electrical energy. 2. A method of transmitting pictures from flexible sheets which comprises cut-ting the sheets to form a series of relatively narrow strips, uniting the strips end to end, moving the flexible band thus formed in the direction of its length. scanning the band transversely waves into electrical energy.

3. A method of transmitting pictures from sheets to form a series of 'relativel narrow strips, uniting the strips end to en moving the flexible band thus formed in the'direc tion of its length, scanning the band transversely thereof, converting the resulting light waves into electrical energy, reconverting the electrical energy into light waves, re- .cordmg the last named light way es, severing the recorded band to correspond to the first named strips, and ammbling the strips- In testimony whereof I aflix my signature. JOHN LOGIE BAIRD.

2 in relation to the opening28 and cell 8. ,i

thereof, and converting the resulting light 

